Over 10 years and across eighteen films, the Marvel Cinematic Universe has been moving towards a narrative goal, weaving its many stories together with the aim of bringing them all to some great climax. It often seemed an unwieldy, mishandled ambition, but after a steady run of strong films over the past few years, that ambition seeks its realisation in ‘Avengers: Infinity War’, a film so big and with so many characters that, by all rights, it should collapse under its own weight. Turns out though, all that effort over so many years was very much worth it.

Alien warlord Thanos (Josh Brolin, ‘No Country For Old Men’, ‘Inherent Vice’), the Big Bad of the MCU who has long been hiding in the shadows, is finally making his push to acquire the Infinity Stones, which when together will give him the power to cause death on a staggering scale. He is driven by an unwavering moral compass, his belief that sacrificing half for the sake of the other’s survival is worth the cost. All that stands in his way are the Avengers and their allies (including the Guardians of the Galaxy and the people of Wakanda), who must band together quickly to stop Thanos before it’s too late.

After their superb work on the last two Captain America films, directing team Anthony and John Russo and writing team Christopher Markus and Stephen McFeely push the boundaries of the MCU with this gargantuan film, the very definition of blockbuster event cinema. Just the fact that the film is comprehensible at all is an achievement, what with the many distinct clashing tones established in the separate threads of the MCU and the staggering amount of characters involved. As they had with ‘Captain America: Civil War’, this team prove they have the skill and imagination to strike a winning balance between all the many balls in play and still deliver a thrilling piece of entertainment. It’s the first MCU film to properly embrace itself as a ridiculous fantasy film that they all are, and is all for the better for it.

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‘Infinity War’ starts off a little shaky, taking the first act to find its feet. The many narrative threads have to be established, often throwing together the most unexpected character combinations. Some work instantly (Robert Downey Jr’s Iron Man and Benedict Cumberbatch’s Doctor Strange start off strong), while others take a bit of work (the Guardians’ arrival doesn’t stick the landing quite as well, James Gunn’s irreverent style initially at odds with the other tones). This results in some clunky sequences, and while nowhere near as bad as the MCU at its worst, are far from it at its best. You get the sense that the Russo Brothers are having trouble working out initially how to get these balls all rolling, but what quickly becomes apparent is that they have a damn good idea where they’re heading, rollocking at breakneck speed into a far more confident and thrilling second act.

How it finds its feet is through the most unexpected of tricks. Marvel have always gotten flack for how insubstantial their villains have been, but that is far from the case with Thanos. In fact, their method for handling the crazy amount of heroes in the film is to not make any of them the protagonist, but to almost make Thanos the centre of the film. He’s a fascinating villain, guided by an emotional logic that what he is doing is right. He isn’t driven by bloodlust or deep-seated hatred but by unwavering conviction that makes him much more difficult to defeat and infinitely more frightening. Much time is taken to explore his background, his motivations and, in particular, his complicated relationship with his adopted and abused daughter Gamora (Zoe Saldana, ‘Star Trek’, ‘Live By Night’). Family, responsibility, duty of care and the value of life permeates through many of the relationships in ‘Infinity War’, allowing it to find heart in unexpected places. It’s also often a brutal, dark film though, establishing often impossibly high stakes and unafraid to make its characters pay for them.

It is in its last third that ‘Infinity War’ skyrockets, leaving all its faults behind by hitting almost every beat with bravura and precision.

The visual scale of the film is absolutely enormous, but while the Russos might not have as strong an eye as Taika Waititi or Rain Johnson do, their skill with action and rhythm turn the film into an often breathless race to the finish line. Most of the action is saved for the last third, but when it arrives, it’s furiously and brilliantly executed, allowing them to expand on that eye for action they had already demonstrated so beautifully in the Captain America films. When the battle is brought to the doors of Wakanda, the result is one of the best battle sequences we’ve seen on film in a long time - kinetic, immersive and immediate. It is in its last third that ‘Infinity War’ skyrockets, leaving all its faults behind by hitting almost every beat with bravura and precision.

What leaves you reeling is how it all comes together in its thunderous and faultless climax - one that actually delivers in ways that most blockbusters very rarely do. It’s one carefully earned and expertly anticipated by everything that comes before it, and left the whole audience at my screening dumbstruck at just what a ripper of an ending it was.

I’ve always been critical of the Marvel Cinematic Universe, so it’s a big deal when I say this - ‘Avengers: Infinity War’ is a must-see blockbuster event. In fact, I doubt we’ll see a better blockbuster this year. It has its stumbles and doesn’t hit every note perfectly, but when it does, it does so spectacularly. If I could have, I would have turned around, sat in my seat and watched it again right away. ‘Infinity War’ throws down the gauntlet, not just for its genre contemporaries, but for the MCU itself, and who the hell knows where on earth they will take it next. It’ll be a damn agonising wait to find out.